The other day, I was asked to be a guest on The Golden Briefcase podcast over at FirstShowing.net. We were talking about “The Quadrilogy Theory,” or in laymen’s terms, the fourth installments in series. In preparation for the appearance, I hopped on Wikipedia to find a list of fourth films.

It was the most depressing list I had ever read in my life… even more depressing than the list of “Saturday Night Live” movies I found while doing some research on this week’s other big opener, “MacGruber.”

There are very few decent – let alone good or great – fourth films in series. That doesn’t mean that few have been made. Just few have been decent. When you think of fourth films, the first ones that come to mind include “Batman & Robin,” “Superman IV: The Quest for Peace” and “Alien: Resurrection.” All crap.

Sure, there are some that are the exception to the rule, like “Live Free or Die Hard” and “Rambo.” But most of the fourth films are either colossal failures or direct-to-video garbage like those of the “Leprechaun” series. In fact, if you rule out horror movies like “Saw” and “Friday the 13th,” almost every fourth film is a disappointment in some way.

All this leads me to say that “Shrek Forever After” is not that bad. That’s what we’ve come to… evaluating a multi-million dollar summer tent-pole release as “not that bad.” But compared to the putrid third installment of the franchise, it’s at least a step up.

In this film, Shrek is feeling the pressures of fatherhood and the mundane nature of daily life. He longs for his days as a bachelor ogre. When Rumpelstiltskin comes into his life and offers him a deal to relive his bachelorhood, Shrek takes the bait. This sets into motion a sequence of events in which Shrek never existed and Rumpelstiltskin becomes the king of Far Far Away. It’s up to Shrek to fix the past so he can fix the future.

This plot is nothing new. Sure, it’s being compared to “It’s a Wonderful Life,” but it has more in line with “The Santa Clause 3” or the direct-to-DVD Disney film “Cinderella III: A Twist in Time.” For the most part, these time-shift stories do work, and it takes Shrek to new places, so the film’s not just a rehash of the previous ones (which was a big problem with the third film, incidentally).

Look, if you don’t know what to expect from the Shrek films by now, you’ve got a problem. This has much of the same humor. It has its fair share of fart jokes, plenty of awkward moments between Shrek and Donkey and the slapstick scenes you’ve seen in other movies.

On the plus side, this installment leaves behind much of the twisted fairy tale humor that seemed fresh in the first film but was run into the ground in the sequels and other movies like “Hoodwinked,” “Ella Enchanted” and “Happily N’Ever After.”

The bottom line is that this Shrek installment isn’t great. But what were you expecting for the fourth film? In this respect, it’s not that bad, and with the presentation in 3D, it gives another fun way to spend 90 minutes with your kids. Believe me, I’ve seen a lot worse.